Multi-material golf club

ABSTRACT

A golf club including a golf club head having improved mass distribution characteristics. The golf club includes a golf club head that is constructed multiple materials and includes a body member, a mass member, and an interface that allows the mass member to be coupled to the body member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 13/532,068, filed Jun. 25, 2012, currently pending, the contents of which are incorporated in their entireties by reference herein.

FIELD OF THE INVENTION

This invention generally relates to golf clubs, and more specifically to a golf club head having a multi-material construction.

BACKGROUND OF THE INVENTION

Typical iron club heads are solid with flat hitting faces and generally configured as either muscle back or cavity back clubs. Traditionally, all irons were configured as muscle back clubs, which are smooth at the back with low offset, a thin topline and a thin sole. Cavity back irons have a hollowed out back and the club head mass is redistributed to the sole and the perimeter of the club head, which moves the center of gravity lower to the ground and rearward. The weight distribution makes the iron launch the ball higher and increases rotational moment of inertia thereby lowering its tendency to rotate on mis-hits and enlarging the sweet spot.

Some muscle back irons have an interior hollow section, such that the club resembles a muscle back on the outside but the interior hollow section alters the club's mass characteristics. One example is U.S. Pat. No. 4,645,207 to Teramoto et al. The Teramoto patent discloses a set of iron golf clubs in which the iron club is cast by the lost wax method, and the back member is welded at the back of the face member to form a hollow section between the back and face members. As the club changes from a longer iron to a shorter iron, the hollow section is gradually decreased to zero and the sole width is gradually decreased.

Another example is U.S. Pat. No. 4,754,969 to Kobayashi. The Kobayashi patent discloses a set of golf clubs wherein each one-piece club head includes a hollow section behind the striking face. Each of the club heads is made of a stainless steel by, for example, a lost wax casting process. The material of each of the face portions of the club heads is then annealed.

Another example is U.S. Pat. No. 7,126,339 to Nagai et al., which discloses utility golf clubs, which generally include a hollow interior.

There remains a need in the art for an improved iron-type golf club. In particular, there is a need for an iron-type golf club that provides a construction that allows more concentrated placement of discretionary mass.

SUMMARY OF THE INVENTION

The present invention is directed to iron-type golf clubs. The inventive iron-type golf club provides a club head that improves the ability to concentrate discretionary mass placement. As a result, it increases ability to optimize the club head moment of inertia and the center of gravity location.

In an embodiment, an iron-type golf club head comprises a body member including a face defining a front ball-striking surface and a rear surface, a perimeter weight portion, a muscle portion and a hosel. The face extends between a top line, a leading edge, a heel and a toe of the body member. The perimeter weight portion extends rearward from the rear surface of the face and defines an upper cavity of the body member. The muscle portion is an elongate portion of the body member extending from the heel to the toe of the body member and rearward from the leading edge of the face, and the muscle portion defines an elongate receptacle extending from the heel to the toe of the body member. The receptacle only intersects an outermost surface of the golf club head and is adjacent the leading edge of the face and extends rearward from the leading edge of the face. The body member is constructed of a first material that includes a base element. An elongate weight member including an elongate mass member and an elongate interface is disposed in the receptacle so that an outermost surface of the interface is flush with an outermost surface of the muscle portion. The mass member and the interface are coupled at a bond surface. The mass member and the interface are exposed only from a lower surface of the body member that extends rearward from the leading edge of the face. The mass member is constructed of a second material that includes a base element, and the specific gravity of the second material is greater than the specific gravity of the first material. The interface is constructed of a third material that is an alloy of the base element of the second material.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIG. 1 is a rear view of an iron-type golf club head in accordance with the present invention,

FIG. 2 is an exploded rear view of the golf club head of FIG. 1;

FIG. 3 is a perspective rear view of weight members of the golf club head of FIG. 1;

FIG. 4 is an exploded rear view of the weight members of FIG. 3;

FIG. 5 is a rear view of an iron-type golf club head in accordance with the present invention;

FIG. 6 is a perspective rear view of a weight member of the golf club head of FIG. 5;

FIG. 7 is an exploded rear view of the weight member of FIG. 6;

FIGS. 8-11 are perspective views illustrating the steps in a method of construction of the weight member of FIG. 3;

FIG. 12-16 are perspective views illustrating the steps in a method of construction of the elongate weight member of FIG. 6;

FIG. 17 is a perspective rear view of weight members that may be used in the golf club head of FIG. 1;

FIG. 18 is a cross-sectional view, taken along line 18-18, shown in FIG. 17; and

FIG. 19 is a cross-sectional view, taken along line 19-19, shown in FIG. 17.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to golf clubs having heads that include multi-material construction. The inventive construction utilizes golf club heads constructed of multiple materials, with one of the materials interposed and forming an interface between two others. Several embodiments of the present invention are described below.

Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials, moments of inertias, center of gravity locations, loft and draft angles, and others in the following portion of the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount, or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

Referring to FIGS. 1-4, a golf head 10 comprises club head body member 12, a muscle back shell 14 and a plurality of multi-material weight members 16. Body member 12 generally includes a face 18, an upper perimeter weight portion 19 and a hosel 20. Face 18 defines a front, ball-striking surface and a rear surface 22. Face 18 extends between a top line 24, a leading edge 26, a heel portion 28 and a toe portion 30.

Perimeter weight portion 19 includes a top rail 21, a toe rail 23, a heel rail 25, and a central rail 27. Perimeter weight portion 19 extends rearward away from rear surface 22 of face 18 and defines an upper cavity 29. Top rail 21 extends rearward away from an upper edge of face 18 and forms a portion of top line 24 of club head 10. Toe rail 23 extends rearward away from a toe side of face 18 along the perimeter of face 18 and between top rail 21 and central rail 27. Heel rail 25 extends rearward away from a heel side of face 18 between top rail 21 and central rail 27 and is joined with face 18 and hosel 20.

A sole 32 of club head 10 extends between leading edge 26 and a trailing edge 34 in a fore/aft direction and between the heel and toe of club head 10. In the present embodiment, sole 32 is constructed by a combination of portions of body member 12, muscle back shell 14, and weight members 16. In particular, leading edge 26 of body member 12 forms a front edge of sole 32 that generally extends between heel portion 28 and toe portion 30. A lower surface 36 of muscle back shell 14 forms a central portion of sole 32. Lower surfaces 38 of weight members 16 form heel and toe portions of sole 32.

Weight members 16 are disposed at the heel and toe ends of club head 10. Each of weight members 16 is constructed as a multi-material component. For example, each weight member 16 includes a mass member 40 and an interface 42 that are constructed from different materials. Mass member 40 provides the majority of the mass of weight member 16 and is coupled to interface 42. Preferably mass member 40 is coupled to interface 42 by a metallurgical bond. As used herein, a metallurgical bond is a coupling wherein two materials are in intimate contact so that they share electrons between the two materials, there is preferably no porosity or gaps at the interface and no intermediate bonding material, such as brazing material or solder, is used. Some porosity, however, may be present even with a metallurgical bond as a result of the particular process. For example, powder metallurgy may result in some porosity within the mated parts. Methods of creating the metallurgical bond include cladding, diffusion bonding, cold-rolling, co-forging and co-molding or co-sintering.

Interface 42 provides a portion of weight member 16 that is constructed with a shape and material that may be easily coupled to body member 12 and muscle back shell 14. Preferably, the mass member and the body member are constructed of materials that have different base elements, such as a mass member with tungsten as a base element and a body member with iron as a base element. In an example, mass member 40 is constructed from a high specific gravity tungsten-nickel alloy, and interface 42 is constructed from a lower specific gravity tungsten-alloy that is capable of being welded to a steel body member 12 and a steel muscle back shell 14.

The components of weight members 16 are preferably coupled by a metallurgical bond. In an example, a pre-form of interface 42 is constructed by compressing the interface material, in powder form, into a pre-form 43 that receives a pre-form 41 of mass member 40. The pre-form of mass member 40 is similarly constructed by compressing the mass member material, in powder form, into the desired pre-form shape. Pre-forms of interface 42 and mass member 40 are illustrated in FIG. 4 prior to their coupling. The interface pre-form 43 defines a receptacle 45 that is shaped to receive the mass member pre-form 41. The pre-forms are fit together to form a combined pre-form that is then compressed and heated until the pre-forms fuse together into weight member 16. Generally, the pre-forms are constructed with larger dimensions than the final dimensions of each of those parts after being fused to allow for dimensional changes during the fusing process, i.e., the dimensions are selected to provide for shrinkage caused by sintering powder metallurgy parts.

Muscle back shell 14 is a thin metallic member that attaches to body member 12. In particular, muscle back shell 14 includes a heel 44, a toe 46 and a sole 48 that are coupled to body member 12. Muscle back shell 14 is coupled to the lower portion of body member 12 and to central rail 27 of perimeter weight portion 19. Muscle back shell 14 includes a heel step 50 and a toe step 52 that, when combined with body member 12, form heel and toe receptacles for weight members 16. The receptacles may be open to a lower cavity of golf club head 10 or muscle back shell 14 may include walled recesses that close one or both receptacles from the lower cavity. In the present embodiment, the receptacles are open to the lower cavity and weight members 16 are coupled to body member 12 and muscle back shell 14 by coupling interface 42 to the perimeter of the receptacle such as by welding.

As an alternative, additional material may be included in muscle back shell 14 and/or interface 42 and the extra material may be used as weld material. As an example, the extra material may be incorporated by including ridges on the outer surfaces of shell 14 and/or interface 42 adjacent the boundary between the parts. The extra material may then be heated by an energy source, such as a laser, and melted so that it flows into the space between muscle back shell 14 and weight member 16 and forms a weld providing a mechanical coupling between the parts.

In another embodiment, shown in FIGS. 5-7, a golf club head 70 includes a body member 72 and a multi-material weight member 74. Body member 72 is generally constructed as a cavity back iron that includes an upper cavity portion and a lower muscle back portion. Body member 72 includes a face 76, a perimeter weight portion 78, a muscle portion 80, and a hosel 82. Face 76 defines a front, ball-striking surface and a rear surface 77. Face 76 extends between a top line 84, a leading edge 86, a heel 88 and a toe 90.

Perimeter weight portion 78 extends rearward away from rear surface 77 and defines an upper cavity 79. Perimeter weight portion 78 includes a top rail 92, a toe rail 94 and a heel rail 96. Top rail 92 extends rearward from face 76 and forms a portion of top line 84 of club head 70. Toe rail 94 extends rearward from a toe portion 98 of face 76 and along the perimeter of face 76. Heel rail 96 extends rearward from a heel portion 100 of face 76, generally along the perimeter of face 76, and merges with a lower portion of hosel 82. Toe rail 94 and heel rail 96 also extend between top line 84 and muscle portion 80.

Muscle portion 80 forms a lower portion of body member 72 and is an elongate portion of golf club head 70 that extends from heel to toe. Preferably, muscle portion 80, face 76, perimeter weight portion 78 and hosel 82 are constructed as a monolithic body, such as by forging or casting a metallic material, such as a steel or titanium alloy. Muscle portion 80 includes a receptacle 102 that extends into muscle portion 80 from a lower surface of muscle portion 80 and is shaped and sized to receive, and to be coupled to, weight member 74.

Weight member 74 includes an interface 104 and a mass member 106. In weight member 74, interface 104 and mass member 106 are both elongate members and are coupled together to form weight member 74. Interface 104 provides a portion of weight member 74 that is constructed with a shape and material that may be easily coupled to body member 72 in receptacle 102. Interface 104 extends between a heel end 108 and a toe end 110. In the present embodiment, the thickness of interface 104 between an inner surface 112 and an outer surface 114 is generally constant. The width of interface 104, between a leading edge 116 and a trailing edge 118, may vary between heel end 108 and toe end 110. The width of interface 104 is generally selected to match a desired width of mass member 106. Preferably, interface 104 is constructed from a material that is capable of being welded to a steel body member 72.

Mass member 106 provides the majority of the mass of weight member 74 and is coupled to interface 104 by a metallurgical bond. Mass member 106 has a varying thickness and includes heel portion 120 and toe portion 122 that have greater thickness than a central portion 124. In an example, mass member 106 is constructed from a high density tungsten-nickel alloy, and interface 104 is constructed from a lower density tungsten-nickel alloy that is capable of being welded to a steel body member 72.

In an example, a pre-form of interface 104 is constructed by compressing the interface material, in powder form, into a pre-form. The pre-form is generally shaped the same as the final configuration of interface 104, but it is dimensionally larger to allow shrinkage during steps of compression and fusing. Similarly, a pre-form of mass member 106 is constructed by compressing the mass member material, in powder form, into a pre-form and the pre-form of mass member 106 is also dimensionally larger than the final mass member 106 to provide for shrinkage during forming. In the present embodiment, the pre-forms of interface 104 and mass member 106 are stacked in a mold and the stacked pre-forms are compressed and heated until they become fused together.

Golf club head body member 72 is preferably made from a lower density material than mass member 106, and preferably is made from a lower density material than interface 104. Preferably, body member 72 has a density in the range of about 4 g/cm³ to about 8 g/cm³, interface 104 has a density in the range of about 4 g/cm³ to about 12 g/cm³, and mass member 106 has a density in the range of about 12 g/cm³ to about 19 g/cm³. Suitable materials for club head body member 72 include, but are not limited to, aluminum, stainless steel or titanium and alloys thereof. Suitable materials for interface 104 include, but are not limited to materials having a base element of aluminum, iron, copper, nickel, zinc, tin, titanium, lead, tungsten, tantalum, gold, platinum or silver and alloys thereof. Suitable materials for mass member include, but are not limited to, materials having a base element of lead, tungsten, tantalum, gold, platinum, molybdenum, hafnium, niobium or silver and alloys thereof. These material alternatives are applicable to all of the embodiments described herein.

Referring to FIGS. 8-11, the steps in a process of constructing another example of weight member 16 will be described. In a first step, a plurality of first members 140 are formed, by forging, casting, pressing, machining, etc. into a desired shape. In the present embodiment, first members 140 are generally shaped as blocks having a trapezoidal cross-sectional shape. A second member 142 is constructed to have a plurality of cavities that are shaped to receive the first members 140. First members 140 are constructed from the material of mass member 40 and second member 142 is constructed from the material of interface 42. Preferably, the materials have different densities and the material of interface 42 has properties that allow it to be easily coupled to the material of body member 12.

The first members 140 are inserted into the second member 142 and the combination is subjected to a joining process. The members may be rolled together, co-forged, or diffusion bonded so that first members 140 form a metallurgical bond with second member 142. The coupling process results in a weight member pre-form 144, as shown in FIG. 9. In the pre-form, the dimensions of both first members 140 and second member 142 have been altered by the coupling process, but the plurality of members are coupled so that they combine to form a single integral unit.

In an example, tantalum may be used for the first members 140 and steel or titanium is used for the second member 142. Tantalum is generally soft and malleable at room temperature and has a very good affinity for titanium and steels, which makes it a good candidate for bonding with golf club heads that are constructed of either steel (e.g, irons) or titanium (e.g., metalwoods). Further, tantalum metal has a density of about 16.6 g/cc which is significantly greater than steel and titanium, which makes it a suitable weight material. The first members may be inserted into cavities of the second member and the combined members may be heated and co-forged. The metal-to-metal contact and elevated temperatures shear any oxide layer that has developed on either component and provides a fresh metal-to-metal contact thereby creating a good metallurgical bond. Additionally, in some embodiments further heat treatment may increase the level of diffusion of the forged component, for example, beta annealing forged titanium alloys.

In another example, tantalum first members 140 are press fit into a steel or titanium second member 142. Then the combined members are rolled under high pressure so that the components metallurgically bond to each other. The pieces may be heated prior to rolling and/or as a subsequent heat treatment.

As a still further option, a weight member may be constructed with first members 140 welded to second member 142. Tantalum provides an advantage for weight members because its density is high relative to titanium and it may be welded to titanium. As a result, first members 140 constructed of tantalum may be welded to a second member 142 constructed of titanium. Then the second member, acting as an interface, may be welded to a titanium club head body. By including the second member as an interface, the manufacturing of the weight is simplified because it is easier to manipulate and fixture the first and second members separate from an entire golf club head body. It is also possible to weld a tantalum weight member directly to a titanium golf club head.

After the pre-form 144 is created, a piece is cut away from the pre-form 144 to create a weight member blank 146. The weight member blank 146 is a component that is constructed from a portion of first member 140 and a portion of second member 142. In the present embodiment, weight member blank 146 is a rectangular block having a multi-material construction. The shape of weight member blank 146 is altered, such as by machining, to create a weight member 16 having a desired shape for the final assembly with body member 12 and muscle back shell 14.

Referring now to FIGS. 12-16, the steps in another exemplary process of constructing weight member 74 will be described. For example, weight member 74 may be constructed using a process such as cladding, in which two materials are metallurgically bonded using a rolling process. For example, a tantalum alloy sheet 150 and a steel sheet 152 may be rolled together by a roller system 154 so that pressure and heat is created between the sheets and they become metallurgically bonded, as shown in FIG. 12. The rolling process couples the two sheets into an integrated sheet 156 in which the different materials are bonded together without requiring an adhesive or brazing material, shown in FIG. 13.

After the different materials are coupled, the integrated sheet 156 may be formed so that it has an intermediate shape, as shown in FIG. 14. After the integrated sheet 156 has been partially formed, it is partitioned into pieces more similar to the final size of weight member 74 so that a plurality of weight member blanks 158 is formed. Finally, blank 158 is machined to the final configuration of weight member 74. For example, and as shown in FIG. 16, a central portion of blank 158 may be removed so that the mass is more concentrated at the ends of the blank. As a result, in the final weight member 74 the mass will be more concentrated on heel and toe ends of weight member 74.

Another embodiment of weight members that may be included in golf club head 10 are illustrated in FIGS. 17-19. Each of weight members 160 is constructed as a multi-material component. For example, each weight member 160 includes a mass member 162 and an interface 164 that are constructed from different materials, and in the present embodiment, interface 164 forms a shell over a majority of the outer surface of mass member 162. Mass member 162 provides the majority of the mass of weight member 160 and is coupled to interface 164. Preferably mass member 162 is coupled to interface 164 by a metallurgical bond. Interface 164 provides an outer shell portion of weight member 160 that is constructed with a material that may be easily coupled to the golf club body member and the muscle back shell. In an example, mass member 162 is constructed from a high density tungsten-nickel alloy, and interface 164 is constructed from a lower density tungsten-nickel alloy that is capable of being welded to a steel body member and a steel muscle back shell, such as a 10 g/cc tungsten nickel alloy.

The components of weight members 160 are preferably coupled by a metallurgical bond. In an example, mass member 162 is constructed by compressing the high density material, in powder form, into a selected shape. As shown in FIGS. 18 and 19, mass member 162 may include features that position it within a secondary mold for the interface material. In particular, those positioning features may include projections 166 that extend from one or more surfaces of mass member 162. Preferably, projections 166 are included on portions of mass member 162 that are directed to the interior of the completed golf club head, so that if interface material does not fully cover the projections, they will not form any part of the outer surface of the complete golf club head.

Interface 164 may be formed in a mold that receives mass member 162 prior to the insertion of interface material. For example, mass member 162 may be inserted into the mold and centered in the mold by projections 166. A powder form of the interface material may then be introduced into the mold around mass member 162 and the combination compressed and heated, preferably in a ceramic mold, to form interface 164 around mass member 162 and to fuse the two materials.

As described, the components of the weight members may be constructed independently or together. For example, each component may be formed using powder metallurgy separately and then the two parts combined and further compressed and heated together so that they bond. In another example, a first component is created, such as by casting, forging or powder metallurgy, and placed in a mold. The material of a second component, in powder form, is placed in the mold around a portion or all of the first component and the combination is compressed and heated. In a still further example, two or more materials in powder form are located in a mold relative to each other as desired in the final weight member, and the combined powders are compressed and heated.

While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objectives stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention. 

We claim:
 1. An iron-type golf club head, comprising: a body member including a face defining a front ball-striking surface and a rear surface, a perimeter weight portion, a muscle portion and a hosel, wherein the face extends between a top line, a leading edge, a heel and a toe of the body member, wherein the perimeter weight portion extends rearward from the rear surface of the face and defines an upper cavity of the body member, wherein the muscle portion is an elongate portion of the body member extending from the heel to the toe of the body member and rearward from the leading edge of the face, wherein the muscle portion defines an elongate receptacle extending from the heel to the toe of the body member, wherein the receptacle only intersects an outermost surface of the golf club head and is adjacent the leading edge of the face and extends rearward from the leading edge of the face, wherein the body member constructed of a first material that includes a base element; and an elongate weight member including an elongate mass member and an elongate interface is disposed in the receptacle so that an outermost surface of the interface is flush with an outermost surface of the muscle portion, wherein the mass member and the interface are coupled at a bond surface, wherein the mass member and the interface are exposed only from a lower surface of the body member that extends rearward from the leading edge of the face, wherein the mass member is constructed of a second material that includes a base element, wherein the specific gravity of the second material is greater than the specific gravity of the first material, and wherein the interface is constructed of a third material that is an alloy of the base element of the second material.
 2. The golf club head of claim 1, wherein the third material has a specific gravity that is less than the specific gravity of the second material.
 3. The golf club head of claim 1, wherein the second and third materials are different tungsten alloys.
 4. The golf club head of claim 1, wherein the first and third materials are weldable to each other, and wherein the first and second materials are not weldable to each other.
 5. The golf club head of claim 1, wherein the interface is bonded to the body member by welding.
 6. The golf club head of claim 1, wherein the interface is constructed with a constant thickness from the outermost surface toward the top line of the body member.
 7. The golf club head of claim 1, wherein the mass member and the interface are coupled only on a single surface.
 8. The golf club head of claim 7, wherein the mass member has a varying thickness from the interface toward the top line of the golf club head, wherein the varying thickness includes at least one of a heel portion and a toe portion of the mass member that has a greater thickness than a central portion that is interposed between the heel portion and the toe portion.
 9. The golf club head of claim 1, wherein the interface defines a width between a weight member leading edge and a weight member trailing edge, wherein the mass member defines a width corresponding to the direction of the width of the interface, and wherein the width of the interface is equal to the width of the mass member. 